Laser scanners are widely-used devices for decoding machine-readable indicia such as barcodes. Laser scanners typically operate by sweeping a laser beam across the laser scanner's field of view. If the field of view contains indicia (e.g., an indicium), the laser scanner receives the laser light that is reflected off the indicia and converts the optical signal into an electrical signal that can be decoded by the laser scanner.
To achieve the effect of sweeping the laser across the field of view, the laser scanner typically has a laser source directing a laser beam at an oscillating light-deflecting assembly. The light-deflecting assembly has a resonant oscillation frequency. Typically, it is desirable to drive the light-deflecting assembly at an oscillation frequency that is offset by some predetermined amount (e.g., 2 Hz, 0 Hz) from the resonant oscillation frequency. Achieving this desired offset has traditionally required repeated resonance testing of the light-deflecting assembly to determine its resonant frequency, which can change over time and temperature. This resonance testing technique can result in unwanted variation in selected drive frequency due to variation in the resonant frequency check method.
Therefore, a need exists for a method for operating an indicia reader that provides for a simplified, yet effective, technique of monitoring the relationship between the drive frequency and the resonant oscillation frequency of the light-deflecting assembly.